Nmcli

- Added rescan parameter to `nmcli.device.wifi`.

- Added support for encodings other than UTF-8.

- Fixed a problem with environment variables being scraped.

- Include LICENSE.txt in the tar.

- Added fields option to `nmcli.device.show` and `nmcli.device.show_all`

- Handle connection failure exceptions with `nmcli.device.wifi_connect`.
- Added wait param to `nmcli.connection.delete`, `nmcli.connection.up`, `nmcli.connection.down`, `nmcli.device.connect`, `nmcli.device.disconnect`, `nmcli.device.delete`, `nmcli.device.wifi_connect`.